Exasol
The Exasol database support is integrated since PDI version 4.3 RC (see PDI-7285)
JDBC driver
Please contact Exasol directly to get the latest and JDBC driver suitable to your server version.
Copy the JDBC driver jar(s) into your PDI distribution folder data-integration/libext/JDBC.
After restarting PDI, the connection with Exasol can be established.
Best practices
You may define the default schema in the Connection / Advanced / Preferred Schema name
As with any column store database, please consider not using steps that are not optimal from a performance standpoint in this regard (e.g. the Dimension Lookup/Step).